AZ-400 Hard Questions — 25 Difficult Questions

Question 1

Which THREE factors should you consider when designing a release pipeline for a critical production application? (Choose three.)

Accepted Answer

Rollback strategy. A release pipeline for a critical production application must include a rollback strategy (e.g., deployment slots or redeploying a previous artifact) to recover quickly from failed releases, deployment health monitoring (e.g., Application Insights, Azure Monitor) to detect issues early and trigger rollbacks or alerts, and approval gates before production deployment to ensure manual or automated checks are passed. These three factors together minimize downtime and ensure controlled, safe releases.

Answer

Use of service principal with least privilege

Answer

Single environment deployment

Question 2

Your Azure DevOps pipeline deploys to multiple environments (Dev, Test, Prod) using YAML multi-stage pipelines. The Prod deployment requires manual approval. However, the approval gate shows 'Pending' even after an authorized user approves. What is the most likely cause?

Accepted Answer

The approval gate is configured to require approval on the latest commit, but a newer commit was pushed after the approval.. In Azure DevOps, approvals are associated with a specific pipeline run and its commit. When a new commit is pushed after an approval, it triggers a new pipeline run. The new run has its own approval requirement, so it remains 'Pending' until approved. The previous approval does not carry over to the new run.

Answer

The pipeline run was triggered by a PR merge, and the approval needs to be re-applied after the build completes.

Answer

The build pipeline includes a step that modifies the approval settings.

Answer

The approver is not a member of the security group defined in the approval settings.

Question 3

You are designing a source control strategy for a team that uses GitHub Copilot. The team wants to ensure that code suggestions do not include sensitive data. Which approach should you recommend?

Accepted Answer

Configure content exclusions in GitHub Copilot settings to block sensitive data patterns. GitHub Copilot's content exclusions allow you to define patterns (e.g., regex for API keys, tokens, or PII) that Copilot will block from being used as context for code suggestions. This directly prevents sensitive data from appearing in suggestions without disabling the tool entirely. It is the most targeted and least disruptive approach to meet the team's goal.

Answer

Use pre-commit hooks to scan for secrets

Answer

Disable GitHub Copilot for the organization

Answer

Enable secret scanning for the repository

Question 4

Refer to the exhibit. The JSON above shows a branch policy configuration for the main branch in Azure Repos. A developer pushes a third commit to an existing pull request after two reviewers have already approved. What happens?

Accepted Answer

The existing approvals remain valid because dismiss_stale_reviews is false.. In Azure Repos, the 'Block on last push' policy (require_last_push_approval) only revokes an approval from the user who made the most recent push, preventing them from approving their own changes. It does not invalidate approvals from other reviewers. The setting that resets all approvals when new commits are pushed is 'Reset code reviewer votes when there are new changes' (dismiss_stale_reviews). Since dismiss_stale_reviews is false in the given configuration, the two existing approvals remain valid when the developer pushes a third commit.

Answer

The pull request is automatically merged because allowed merge types include squash.

Answer

The approvals are dismissed because require_last_push_approval is true.

Answer

The pull request is blocked because the merge type is not allowed.

Question 5

Your release pipeline deploys to multiple environments (Dev, Test, Prod) using approval gates. Recently, the Prod deployment failed because a manual validation task timed out after 30 minutes. You need to ensure that if the manual validation is not approved within 15 minutes, the pipeline automatically rejects the deployment and sends a notification. What should you do?

Accepted Answer

In the Manual Validation task, set 'Timeout' to 15 and 'On timeout' to 'Reject'.. The Manual Validation task has a 'Timeout' setting and an 'On timeout' option. Setting Timeout to 15 minutes and On timeout to 'Reject' will automatically reject the deployment if not approved within 15 minutes. Additionally, you can configure a notification using an Azure DevOps subscription or service hook for the rejection event. Option A is incorrect because the stage timeout does not specifically handle manual validation rejection. Option C is incorrect because, although pre-deployment approvals do have a timeout that can reject on timeout, they apply to the approval gate before the stage, not to a manual validation task within the stage. Option D is incorrect because adding a PowerShell task is unnecessary and less reliable than the built-in timeout behavior.

Answer

Set the 'Timeout in minutes' for the entire stage to 15.

Answer

Configure a pre-deployment approval with a timeout of 15 minutes.

Answer

Add a PowerShell task after the manual validation that checks the status and cancels the pipeline if not approved.

Question 6

You have the YAML pipeline exhibit above. The pipeline fails with: 'The pipeline is not valid. Could not find the template file shared-templates/build-steps.yml.' What is the most likely cause?

Accepted Answer

The template path is incorrect because it should be relative to the repository root; the repository name is 'myorg/shared-templates', so the path should be 'build-steps.yml'.. When referencing a template from another repository in Azure Pipelines, the `repository` property specifies the repository name (e.g., `myorg/shared-templates`), and the template path must be relative to the root of that repository. The error indicates the pipeline cannot find the file, meaning the path `shared-templates/build-steps.yml` is incorrect; it should be just `build-steps.yml` since the repository name is already declared in the `repository` field. The path should not include the repository name again.

Answer

The checkout step for 'shared-templates' must be before the template reference, which it is.

Answer

The template file is missing from the shared-templates repository.

Answer

The ref 'refs/heads/main' does not exist in the shared-templates repository.

Question 7

Your organization uses GitHub Actions for CI/CD. You need to ensure that deployment to production only occurs after a successful deployment to a staging environment and requires approval from a senior developer. The deployment workflow is defined in a single YAML file. What is the most efficient way to achieve this?

Accepted Answer

Use two environments (staging and production) with required reviewers on the production environment, and use conditional steps to deploy to staging first.. GitHub Actions supports deployment environments with required reviewers. By defining separate 'staging' and 'production' environments, you can use a conditional step to deploy to staging first, and then require manual approval from a senior developer before the production deployment proceeds. This approach is built into GitHub Actions and does not require external webhooks or manual workflow triggers, making it the most efficient and secure method.

Answer

Add a step that pauses the pipeline until a manual approval is received via a custom webhook.

Answer

Use a workflow_dispatch trigger and require the senior developer to manually run the production deployment.

Answer

Use a build matrix to run staging and production deployments in parallel.

Question 8

Your team is migrating from TFVC to Git in Azure Repos. Developers frequently work on the same files simultaneously. Which Git workflow should you recommend to minimize merge conflicts?

Accepted Answer

Feature branch workflow. The feature branch workflow is ideal for minimizing merge conflicts when developers work on the same files simultaneously because each developer creates a short-lived branch off the main branch for their specific feature or fix, commits frequently, and merges back via pull requests. This isolates changes until they are ready, reducing the surface area for conflicts compared to long-lived branches. Git's merge or rebase strategies within this workflow allow for incremental conflict resolution, which is more manageable than resolving large conflicts from divergent histories.

Answer

GitFlow

Answer

Forking workflow

Answer

Centralized workflow

Question 9

Which THREE components are required to set up a self-hosted agent pool in Azure Pipelines?

Accepted Answer

The agent software installed on the target machine. To set up a self-hosted agent pool in Azure Pipelines, you must install the agent software on the target machine (option A), which provides the listener that polls Azure DevOps for jobs and runs them locally. You also need to configure the agent with the agent pool name and the URL of the Azure DevOps organization (option C), since the agent registers itself into a specific pool under a specific organization endpoint. Authentication requires a personal access token (option E) with the appropriate scope (typically Agent Pools read/manage), which the agent uses during configuration to register with the service. Option B is incorrect because deployment groups are a separate feature for classic release pipelines targeting machines, not the mechanism for creating an agent pool. Option D is incorrect because the Azure VM extension for Azure Pipelines Agent is an optional convenience for provisioning agents on Azure VMs, not a required component of a self-hosted agent pool.

Answer

A deployment group target

Answer

Azure VM extension for Azure Pipelines Agent

Question 10

Your release pipeline deploys a .NET Core web app to Azure App Service using a slot swap strategy. The pipeline runs acceptance tests on the staging slot before swapping. After a recent change, the acceptance tests pass but the production site becomes unresponsive after the swap. What is the most likely cause?

Accepted Answer

The staging slot had different app settings that were swapped into production, causing the site to fail.. The most likely cause is that the staging slot had different app settings (e.g., connection strings, environment variables, or feature flags) that were swapped into production. During a slot swap, Azure App Service automatically moves all slot-specific configuration (app settings, connection strings, and other deployment slot settings) to the target slot. If the staging slot was configured with settings intended only for testing (like a staging database or debug mode), those settings would overwrite the production settings, causing the production site to become unresponsive. This is a common pitfall because acceptance tests may pass against the staging environment but fail when the same code runs with production configuration.

Answer

The acceptance tests are not comprehensive enough and missed a regression.

Answer

The acceptance tests should have been run after the swap.

Answer

The slot swap was not 'warm-up' and caused downtime.

Question 11

You are designing a build pipeline for a .NET Core application. You need to ensure that the pipeline restores NuGet packages from both an Azure Artifacts feed and the public NuGet gallery. The pipeline must fail if a package is not found in either source. Which two actions must you take? (Select two.)

Accepted Answer

Create a NuGet.config file that includes both feeds as package sources and reference it in the restore task.. Creating a NuGet.config file that includes both the Azure Artifacts feed and the public NuGet gallery as package sources, and referencing it in the restore task, ensures the pipeline consults both sources. Option D is incorrect because the 'CheckConsistency' flag is not related to failing on missing packages; the restore task already fails by default if a package cannot be resolved from any configured source. Options B, C, and E do not fulfill the requirement to fail on missing packages from both sources.

Answer

Set the 'NoWarn' property to NU1603 to ignore warnings about missing packages.

Answer

Use the 'dotnet restore' task with the '--no-cache' flag.

Answer

Set the 'CheckConsistency' flag to true in the restore task.

Answer

Configure the Azure Artifacts feed to use the public NuGet gallery as an upstream source.

Question 12

Your organization uses GitHub for source control and GitHub Actions for CI/CD. You need to implement a branching strategy where every commit to the main branch triggers a build and deployment to a staging environment, but only after a successful pull request review. Which GitHub Actions trigger should you use?

Accepted Answer

push with branches: [main]. The `push` trigger with `branches: [main]` runs on every commit pushed to main. When branch protection requires pull request reviews, commits only reach main through a reviewed and merged PR, so this satisfies the 'only after successful pull request review' condition. In contrast, `pull_request_target` with `types: [closed]` triggers for any closed PR, including those not merged, and does not map one-to-one to commits on main. To use a PR event, you would need an additional condition like `if: github.event.pull_request.merged == true`, which is not mentioned.

Answer

pull_request_target with branches: [main] and types: [closed]

Answer

pull_request with branches: [main]

Answer

workflow_dispatch

Question 13

Which THREE conditions must be met for you to use the 'Approvals' feature in Azure Pipelines to control deployments to a production environment? (Choose three.)

Accepted Answer

The approver must have the 'Approve pipeline permissions' permission for the environment.. The 'Approvals' feature in Azure Pipelines requires an environment to be defined in the pipeline. You must add an approval check to that environment, which can be done in either a classic release pipeline or a YAML pipeline that references the environment as a resource. Additionally, the approver(s) - whether individual users or groups - must have the 'Approve pipeline permissions' permission on that environment. Without an environment resource, the approval check cannot be configured; without the permission, approval requests cannot be validated.

Answer

The approver must be an individual user, not a group.

Answer

The approval must be configured in the release pipeline's pre-deployment conditions.

Question 14

Your organization uses GitHub and wants to implement a monorepo strategy for multiple related projects. Which approach best optimizes CI/CD pipeline performance by only building projects that have changed?

Accepted Answer

Use path filters in GitHub Actions workflows. GitHub Actions path filters (using `on.push.paths` or `on.pull_request.paths`) allow you to trigger workflows only when changes are made to specific directories or files. In a monorepo, this ensures that CI/CD pipelines run exclusively for the projects that have been modified, avoiding unnecessary builds and significantly improving performance.

Answer

Use a single workflow that builds all projects on every push

Answer

Use submodules to separate projects

Answer

Use workflow templates and composite actions

Question 15

Your organization uses GitHub Actions and has a repository containing sensitive infrastructure code. You need to ensure that only approved actions are used in workflows. Which two settings should you configure? (Select two.)

Accepted Answer

Allow actions created by GitHub.. This is a select-two question. The correct answers are A and C. Option A is correct because enabling 'Allow actions created by GitHub' restricts workflows to only use first-party actions published by GitHub, establishing a baseline security posture. Option C is correct because further limiting actions to only those from specific approved repositories provides granular control over third-party actions that have been vetted by the organization. Together, these settings ensure that only approved actions can be used in workflows, meeting the compliance requirement.

Answer

Disable actions for the repository.

Answer

Use environment protection rules.

Answer

Store actions in encrypted secrets.

Question 16

Refer to the exhibit. A build pipeline uses this trigger configuration. A developer pushes a commit to the 'main' branch that modifies files in '/src/app/' and '/src/tests/'. How many builds will be triggered?

Accepted Answer

1 build, because batchChanges is true.. The trigger configuration has `batchChanges` set to `true`. When `batchChanges` is enabled, Azure Pipelines groups all commits that arrive while a build is in progress into a single build, rather than triggering a separate build for each commit. In this scenario, the developer pushes a single commit that modifies files in both `/src/app/` and `/src/tests/`. Since `batchChanges` is true, only one build is triggered for that commit, regardless of the number of modified folders.

Answer

0 builds, because the excluded path takes precedence.

Answer

3 builds, because maxConcurrentBuildsPerBranch is 1 but batchChanges overrides.

Answer

2 builds, one for each modified folder.

Question 17

A company uses Azure Pipelines to build a .NET Core application. The build takes 45 minutes due to dependency restoration. They want to reduce build time. What is the most effective strategy?

Accepted Answer

Cache the NuGet packages and enable caching in the pipeline. Caching NuGet packages in Azure Pipelines is the most effective strategy because dependency restoration is the primary bottleneck, often downloading hundreds of packages from nuget.org. By caching the ~/.nuget/packages folder, subsequent builds skip the network download entirely, reducing the 45-minute build time to minutes. This directly addresses the root cause—repetitive package restoration—without requiring additional infrastructure or parallelism.

Answer

Use parallel jobs in the pipeline

Answer

Use a self-hosted agent with more CPU

Answer

Enable incremental builds

Question 18

The pipeline fails because the artifact is empty. What is the most likely cause?

Accepted Answer

The build output is not copied to the staging directory. The most common reason for an empty artifact in Azure Pipelines is that the build output files were not copied to the staging directory (typically $(Build.ArtifactStagingDirectory)) before the PublishBuildArtifacts task runs. The PublishBuildArtifacts task publishes whatever is in the staging directory; if no files are copied there, the artifact will be empty. This is a standard pattern where a Copy Files task or similar step must explicitly place the build outputs into the staging directory.

Answer

The projects pattern '**/*.csproj' does not match any files

Answer

The task 'PublishBuildArtifacts@1' is misspelled

Answer

The artifact name 'drop' is invalid

Question 19

You are the DevOps lead for a financial services company. The company uses Azure DevOps Services with a single project containing multiple teams. The compliance team requires that all production deployments be approved by a change advisory board (CAB) member. Additionally, any deployment that changes a configuration value stored in Azure App Configuration must be audited. You have set up a release pipeline with a manual approval gate and a pre-deployment condition that runs a PowerShell script to validate configuration changes. However, the compliance team reports that some deployments bypassed the approval gate. Upon investigation, you find that developers with 'Edit release pipeline' permissions can modify the pipeline and remove the approval gate. You need to ensure that the approval gate cannot be bypassed by developers. You also need to ensure that any change to a configuration key is logged to Azure Monitor. What should you do?

Accepted Answer

Create a protected variable group that stores the approval gate configuration and set the pipeline to use it. Restrict edit permissions on the release pipeline to a security group that does not include developers. For configuration changes, use an Azure Resource Manager template with a deployment script that sends logs to Azure Monitor.. It addresses both requirements: restricting pipeline edit permissions to a security group that excludes developers prevents them from removing the approval gate, and using an ARM template with a deployment script that sends logs to Azure Monitor ensures configuration changes are audited. Protected variable groups secure sensitive configuration, but the key is permission separation and audit logging via ARM deployment scripts.

Answer

Create a new service connection with limited permissions and require that all pipeline runs use it. Use an Azure Policy to audit configuration changes.

Answer

Configure environment-level approvals in the release pipeline and use Azure Policy to enforce that all deployments go through the environment. Use diagnostic settings on App Configuration to stream logs to Azure Monitor.

Answer

Implement a branch policy on the release pipeline's YAML file in the repository to require approval for changes. Use a webhook to send configuration change events to Azure Monitor.

Question 20

Refer to the exhibit. The workflow runs successfully but the deployment fails because the Azure CLI is not authenticated. What should you add to the workflow to authenticate?

Accepted Answer

Add the 'azure/login' action with Azure credentials. The Azure CLI in the workflow requires authentication to interact with Azure resources. Adding the 'azure/login' action with valid Azure credentials (e.g., service principal secrets or OpenID Connect) establishes the necessary authentication context before any Azure CLI commands are executed, resolving the 'not authenticated' error.

Answer

Add the 'actions/setup-node' action

Answer

Add the 'azure/webapps-deploy' action

Answer

Add the 'actions/github-script' action to use the GitHub token